Code

 Header...
//
// Print the lowest factor of an integer or say that it is prime.
// Written to illustrate the while() loop
// The basic algoritm is to try every possible factor up to the square
// root of the number being looked at (the target)
//

 int main(){
   ... 

»  int target, factor, maxfactor;

»  target=55;

»  maxfactor=sqrt(target);// Largest factor we need to try

»  factor=2;
»  while (target%factor!=0&&factor<=maxfactor) 
    ++factor;// factor = factor + 1
  
»  if (factor>maxfactor) 
    printf("%d is prime\n", target);
  else 
    printf("\t%d is not prime, its lowest factor is %d\n", 
       target, factor);

»  return 0;
}

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